Researchers in Dr. Maris' laboratory previously established that LOH in a region of chromosome 11 allows aggressive neuroblastoma to take hold. The new microarray can detect such gene defects on chromosome 11 and other genetic regions implicated in neuroblastoma.

Microarrays are silicon chips that contain tightly ordered selections of genetic material upon which sample material can be tested. When DNA bases from a sample bind to complementary sequences on the microarray, they cause fluorescent tags to shine under laser light. This is a signal that a particular gene variation is present in the sample.

"We can test DNA from peripheral blood and from the tumor, and we should see a loss of signal in the cancer," said Dr. Fortina. He noted that the researchers can simultaneously evaluate seven chromosomal regions known to be involved in neuroblastoma.

Unlike gene expression microarrays, which detect varying levels of RNA to measure the activity levels of different genes as DNA transfers information to RNA, the current microarray directly identifies changes in DNA. "These DNA changes, involving gain or loss of genetic material, are important for neuroblastoma prognosis," said Dr. Maris.

In pinpointing specific regions of chromosomes with loss in DNA, the technology may help confirm a clinical diagnosis, said Saul Surrey, Ph.D., professor of medicine and Associate Director of Research at the Cardeza Foundation for Hematologic Research and the Division of Hematology at Jefferson Medical College. If a clinical diagnosis isn't known, the method might provide some clues.

The microarrray described in the paper has only been used in their laboratory study, but the researchers hope that with further study it may become more widely available as a diagnostic too
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1-Aug-2005